CONCURRENCY_LIMIT ignored

[lart2150]

      if (queue.length > CONCURRENCY_LIMIT) {
        await queue.shift()
      }

queue.shift() does not return a promise so this does not wait.

you could do something like

      while (queue.length > CONCURRENCY_LIMIT) {
        await sleep(Math.random(100))
      }

and then in the finally add queue.pop();

This would be a non deterministic queue but it's a simple change to support CONCURRENCY_LIMIT